while driving yesterday the check engine light and the VTM-4 light came on simultaneously. this came on just as I reached my destination so I turned the car off and let it sit for a few hours. when I got back and started the car the check engine light was still on but the VTM-4 was off, and after a few miles of driving the check engine light also went off. then today both lights came back on, and again when I turned the car off(this time for only a few minutes) and then started it the VTM-4 light was off, but then came back after a few minutes. this time both lights stayed on for me to use my obdII scanner and I got the p0131 code for the pre-cat O2 sensor, which seems like a not terribly difficult but very annoying job. my only worry is that in my searching I have not been able to find anyone else mentioning the VTM-4 light coming on with a bad O2 sensor and I don't want to spend money on something that might not be the problem. any insight on the situation would be greatly appreciated.